Millie Bobby Brown Covers Katy Perry’s ‘Firework': Watch

Millie Bobby Brown enchanted Argentina Comic-Con attendees on Friday, May 26 when she treated the crowd at the Netflix panel to an impromptu performance.

After speaking about her Stranger Things character, Eleven, the British actress, who's known for her love of music and singing (especially when it comes to rapping Nicki Minaj verses), sang "Ave Maria" a capella before surprising the crowd with a soulful, stripped down rendition of Katy Perry's "Firework."